1. Field of the Invention
This invention relates to circular saw blades of the type used on electric hand saws; and particularly to such a circular saw blade that will cut an arcuate kerf in lumber.
2. Description of the Prior Art
U.S. Pat. No. 197,688 issued Nov. 27, 1877, discloses a circular saw blade in which openings are provided in the body of the blade so that, in effect, the outer periphery is connected to the "eye" of the saw blade by radially extending arms. In one aspect, the radially extending arms give the entire saw blade a concave configuration. In a second aspect, the arms are detachable from the rim so that a new rim may be attached to the arm structure when the saw blade wears out. Nothing in this patent appears to suggest the capability of cutting an arcuate kerf.
U.S. Pat. No. 207,450 issued Aug. 27, 1878 discloses a circular saw blade in which the saw blade as a whole, is formed into a shallow cone, with the radius of the blade from the center of rotation to the outer periphery being a straight line. Again, nothing in this patent appears to suggest the capability of cutting arcuate kerfs.
U.S. Pat. No. 320,681 issued Jun. 23, 1885 discloses a circular saw blade one side of which is flat and the opposite side of which is generally conical from near the outer periphery to the central "eye". There is no suggestion in this patent relating to cutting an arcuate kerf.
U.S. Pat. No. 4,454,901 relates to a multi-directional planar saw blade having a generally equilateral triangular shape. Toothed truncated end portions are provided on the blade to effect cutting.
It will be seen from the prior art patents noted above that none of the structures heretofore disclosed is structurally similar to my saw blade structure. It appears that only recently has any thought been given to the concept of providing a saw blade for a so-called circular saw that cuts in anything but a rectilinear path. The most recent patent discovered is U.S. Pat. No. 4,454,901, and it is quite obvious from an examination of this patent that structurally there is no comparison between the structure of this patent and that forming the subject matter of my invention.
Typically, both in the do-it-yourself market and in the construction industry, the usual methods for cutting an arc in lumber is to use a so called "jig" or scroll saw, which is capable of producing sharp turns, almost right angles, or a band saw which is capable of cutting a curve having a larger radius, and even a relatively small radius, or a saber saw which utilizes a reciprocating blade to follow a path to be cut in lumber. For large sheets of lumber, the scroll saw and band saw are inconvenient because both of these are saws with a fixed and stationary bed, requiring that the lumber be supported on the bed and manipulated to have the saw blade follow a path to be cut. This can be very difficult when the piece of lumber that is being cut is a 4'.times.8' panel. The saber saw does not have this disadvantage, since it is a hand-held saw in which the saw itself is manipulated and the piece of lumber being cut is held stationary. The disadvantage of a saber saw, as compared with a circular saw, is that it is relatively slow in effecting its cut, and requires extreme care and control during use to effect a smooth cut that accurately follows a prescribed path.
Accordingly, in view of the disadvantages of the conventional methods for cutting curves in lumber, one of the important objects of the present invention is the provision of a circular saw blade that is configured in a manner that it will smoothly follow a prescribed curve or arcuate path.
Another object of the invention is the provision of a circular saw blade for cutting arcs or curves in lumber which may be mounted on the arbor of a conventional electrically driven circular hand-saw of the types that are well known in the industry.
Still another object of the invention is the provision of a circular hand-saw blade that may be configured from a conventional planar circular saw blade to cut curves having different radiuses, thus enabling use of the many different types of saw blade teeth conventionally used on circular saw blades.
The invention possesses other objects and features of advantage, some of which, with the foregoing, will be apparent from the following description and the drawings. It is to be understood however that the invention is not limited to the embodiment illustrated and described, since it may be embodied in various forms within the scope of the appended claims.